Snap on control mechanism



Jan. 11, 1966 BIESECKER 3,228,254

SNAP ON CONTROL MECHANISM Filed May 28, 1963 Fig'z Fig. 4-

TQM/46 INVENTOR. Dona/o L. B/e'sec/(er WMBTQM ATTORNEY United StatesPatent 3,228,254 SNAP 0N CONTROL MECHANISM Donald L. Biesecker, Dayton,Ohio, assignor to Illinois Tool Works Inc., Chicago, 11]., a corporationof Dela- Wille Filed May 28, 1963, Ser. No. 283,900 6 Claims. (31.74-104 This invention relates in general to snap on assemblies and moreparticularly relates to a knob and stem means integral therewith whichare adapted to be inserted through an aperture and snap on to anindependently mounted lever arm member.

Gasoline powered implements and motors, such as outboard engines,generally have a choke control which is manually actuated. For aestheticand for functional reasons the motor and the carburetor associatedtherewith is oftentimes covered by a bezel or housing. Since thecontrols for the motor, such as the choke control, need to be on theexterior for quick actuation thereof by the operator, the assembly ofthe housing over the motor poses some problems. For example, the controlknob, if it is fixedly attached to the lever mechanism which operatesthe choke control, must be made in such a manner that it is possible toassemble the housing over the motor and to this end many times the knobsare detachable so that an extremely large sized aperture need not beprovided so that the housing will fit over the knob. Detachable knobsare objectionable since they often jiggle loose from the vibration ofthe motor or otherwise become detached. A further problem sometimesencountered with the prior art devices relates to the connection betweenthe end of the stem of the knob member and the pivotally mounted armwhich controls the position of the member to be controlled, for example,the butterfly valve in -a carburetor. The pivotally mounted levergenerally is mounted on a pivot whose axis is transverse to thereciprocal movement of the stem of the control knob. To accommodate thecircular path of the end of the lever arm to the reciprocatory motion, apin and slot mechanism is conventional. However, due to the vibration ofthe mechanism and repeated actuation of the lever arm, the pin has atendency, on occasion, to become deformed and to establish unusual wearpatterns and occasionally will get hung up so that relative movementbecomes difiicult.

This invention is concerned with a structure which solves the aforenotedproblems. More particularly, this invention is concerned with a onepiece plastic choke control member or the like which may be made in asingle molding operation and which is exceedingly easy to assemble bothinitially and in field repair situations without the use of additionalfastening means.

Another object of this invention is to provide a control member whichmay be inserted from the exterior of the housing through blind aperturesin a manner to establish a connection between a member to be controlledwhich is remote from the housing aperture and in a manner that isrelatively easy to assemble and which severely retards unauthorizeddisassembly.

It is a further object of this invention to provide an assembly whichserves the dual functions of providing quick snap on attachment anddetent cooperation.

A still further object of this invention is to provide a knob and stemcontrol means which is noncorrosive, is dimensionally stable, withstandsweathering well, is durable for its intended purpose, has no sharpcorners on those portions which are engageable by the human hand and isotherwise well designed for the purposes for which it is used.

A still further object of this invention is to provide 3,228,254Patented Jan. 11, 1966 "ice an assembly which provides the dualfunctions of quick connection and detenti-ng in a manner to eliminateparts and is more economical in materials, and assembly time as comparedto prior art assemblies.

Another object of this invention is to provide a control member which iseasy to tool in such a manner that the aesthetic portion (the knobportion), may be readily changed to impart a versatility of designs ofknob-s while maintaining the functional aspects of the entering end ofthe stem portion essentially unchanged.

The novel features that are characteristic of the invention are setforth with particularly in the appended claims; the invention itself,however, both as to its organization and its method of operation,together with additional objects and advantages thereof, will best beunderstood by the following description of specific embodiments whenread in connection with the accompanying drawings in which:

FIG. 1 is a semi-diagrammatic view of an assembly utilizing the controlmeans which is the subject of this application;

FIG. 2 is a side elevational view of a portion of the detent mechanismused in the assembly shown in FIG. 1;

FIG. 3 is an enlargement of the upper portion of the detent mechanismshown in FIG. 3;

FIG. 4 is a right hand end view of the mechanism shown in FIG. 2;

FIG. 5 is a bottom plan view of the mechanism shown in FIG. 4;

FIG. 6 is a perspective view of one form of control knob and stem memberforming a part of the assembly shown in FIG. 1;

FIG. 7 is a side elevational view of the member shown in FIG. 6, thehead portion thereof being modified in nonfunctional respects;

FIG. 8 is a sectional view along lines 88 of FIG. 7;

FIG. 9 is an end view of the member shown in FIG. 7;

FIG. 10 is a top plan view, partially in section, of the member shown inFIG. 7, the head portion being modified to illustrate another variationof the knob design available;

FIG. 11 is a sectional view taken along lines 11-11 of FIG. 10;

FIG. 12 is a view similar to FIG. 1, with certain portions of theassembly being shovm in section to illustrate the snap on attachmentfeatures of the assembly;

FIG. 13 is a view showing an alternate method of attachment of adilferent lever arm to a member such as shown in FIGS. 6 through 12; and

FIG. 14 is a view of an alternate form of member serving substantiallythe function as the member shown in FIGS. 6 through 11.

Returning now to FIG. 1 of the drawings, an assembly 10 is shownpartially in dotted lines and partially in full lines, the dotted linesshowing the approximate location of a carburetor for an outboard motoror the like and the full line portions 12 show a plurality of leverarms, springs, detent mechanisms and control knob for a manual chokecontrol. More particularly, link 14 in the form of a wire rod isattached to a butterfly valve member (not shown) and in turn is actuatedby a pivotally mounted member 15 which is one arm of a bell crank lever.The other arm 16 of the bell crank lever is springloaded against andactuated by a pivotal lever member 18 which is directly actuated by thecontrol knob means 20.

The control knob means 20 is associated with a detent mechanism 22 to bemore particularly described. The knob means 20 may be inserted throughan outer casing or housing 24 having a grommet means 26 therein, saidknob means being inserted so as to engage the lower arm 28 of pivotalmember 18 which has a cam surface 30 on the bottom thereof as shown inFIGS. 1 and 12. The control knob means 20 is inserted through the detentmeans and through the panel and reciprocates with a straight line motionfrom left to right and right to left as viewed in FIGS. 1 and 12. Thepivot 32, for lever 18, is disposed substantially transversely to theline of motion of the control knob means 20. Thus, lever arm 28 and endsurface 30 thereon'follow a circular path around pivot 32 whichintersects the path of travel of the knob control means 20.

It will be specifically realized that while this invention is to bediscussed in terms of the choke control knob for association with acarburetor and carburetor lever arm, this precise usage is to beconsidered illustrative only, as the control means 20 has a wider fieldof application and use.

The detent means 22 may take the form of a plastic member 36 (shown indetail in FIGS. 2 through which is fixed to a portion 34 of the castingwhich mounts the carburetor means shown in FIG. 1. The plastic member 36may be made of a material such as nylon and is adapted to be insertedinto a hollow, somewhat rectilinearly shaped boss 34, there being stops38 and ears 40 integral therewith which prevent relative movement of themember 36 to the casting boss 34 after assembly of member 36 thereto. Asshown in FIG. 4, the member 36 is split along the bottom side thereof topermit easy insertion into the boss 34, and member 36 is formed with ahollow through bore 42. The two side walls of member 36, defining thebore 42, are substantially parallel to each other so that relativerotation between the shank of the control knob means 20 when the latteris inserted therewithin is prevented. The upper wall of member 36 isformed with a flexible portion 44 having a depending rib 46 whichextends transversely of the bore 42. Due to the relative thickness ofportion 44, rib 46 may move in a vertcal direction upwardly as viewed inFIGS. 2 and 3. Due to the inherent resiliency of the material of whichmember 36 is made, the rib 46 will return to or be biased toward theat-rest positions shown in FIGS. 2 and 3. The rib 46 serves as thedetent means for coaction with the control knob as will become apparentthrough later discussion. While a particular detent means 22 has beenshown and discussed, any of a plurality of different detent means whichwill serve the same function is permissible and does not form the basisof this invention except for the cooperation with the knob means 20.

The control knob means 20 has a generally rectilinear shank portion 48as shown in FIG. 7 with the knob portion 50 of any one of a plurality ofconfigurations, as suitable and desired, at one end thereof and with anentering end means 52 at the opposite end of the shank. Intermediate thetwo ends of the shank and closely adjacent to the entering end portion52 is a portion 62 which cooperates with the detent member 36. As shownin FIG. 8, the intermediate portion 62 has substantially parallelopposed side portions 54 and 56, the top surface 58 and bottom surface60 being substantially transverse to the side walls 54 and 56. Stopmeans 55 on sides 54 and- 56 prevent over-actuation of knob means 20. Asshown in FIGS. 8 and 11, recesses may be made in the essentiallyrectilinear shank portion to reduce the amount of material in the shank.A curvilinear surface 64 connects two depressed areas 66 and 68 whichprovide the end limits of the travel of the control knob in detentcooperation with the rib 46 on member 36.

As can be seen in FIG. 11, the center web 70 separates the recesses in atransverse direction and extends to a position just below the right handdetent recess 66. Outboard of the detent receiving portion 66, to theright as viewed in FIG. 11, is a pair of side extensions 72 and 74,which may be spaced apart a slightly lesser dimension than are sidewalls 54 and 56 as shown in FIGS. 8 and or may be the same as shown inFIG. 6. An extension of center web 70 in the form of an angularlydivergent cross web portion 76 which together with an angularlyextending front cross web portion 78, the arms 72 and 74, and anupwardly extending web portion 75 define an aperture for receipt of thelever member 30 as shall be explained. The nose portion cross web 78 hasa top surface 86 which is spaced slightly below the vertical extent ofthe two arms 72 and 74. It should be further noted that the armextensions 72 and 74 have front extension portions 82 and 84 which arebeveled as best shown in FIG. 10 and extend beyond web 78.

A resilient hinge rib 88 is formed by the cross web 76 by recessingsurface 60 as perhaps best shown in FIG. 11. The structure shown willflex in a downwardly direction around the rib area 88 from the positionshown in FIG, 11 in a manner as shall now be explained.

To assemble the knob control means 20, so as to engage the lever arm 28,the control knob means 20 is merely inserted through the panel 24,grommet 26 and through the aperture 42 in the detent member 36. As theentering end portion progresses through the aperture 42, rotationthereof is prevented due to the cooperation of the sides 54 and 56 withthe side walls of the detent member 36.

Due to the angle of inclination of the web portion 78 and the beveling82 and 84 on the side members 72 and 74, the entering end engages andguides the end 30 of lever 28. As the knob means 20 is forced inwardly,the entering end portion 52 is forced downwardly so as to flex about thehinge rib 88. Lever 28 has only a limited range of travel set by otherlimits so that the rounded end portion 30 coacting with member 78 servesto cam the end portion 52 of the control knob means downwardly until web78 snaps over the end portion 30 to trap lever 28 in the aperture 80.Once the lever 28 and the control knob means 20 are assembled, as shownin FIG. 12, it is difiicult to disassemble same. The beveled lead inportions 82 and 84 and the short portions of the extensions 72 and 74above the top surface 86 of member 78 prevent the lever arm 28 fromtwisting during the downward flexure of the control knob. Onceassembled, the control knob may be actuated between its detent positionby merely reciprocating same. Obviously, the housing 24 and grommet 26are not necessary to'the cooperation involved and hence the presencethereof is permissive.

Another type of lever arm 28a is shown mounted to substantially anidentical control knob means by being inserted from the other side ofthe aperture 80. As shown in FIG. 13, the end portion 30a has a roundedportion which is adapted to ride on the back side f the web portion 78until hook portion 90 engages the top portion 86 thereof. A reverse hookportion 92 on lever arm 28a engages the furthest extent of the webportion 76.

Another embodiment of knob control means 20b is shown in FIG. 14 andserves substantially a similar function. The embodiment shown in FIG. 14is adapted to flex transversely to the flexure of the member shown inFIG. 11. To this end the entering end portion has a cam surface 94 and aplurality of flexure ribs 96. The lever arm member 28 cams portion 94downwardly as viewed in FIG. 14 until the lever arm bottoms on theaperture at 106. At this point the thin web 102 will snap over the edgeof the arm enclosing and trapping the end of a lever arm similar tolever 28. The member 28 is trapped between the extensions 98 and the web102 when the device is assembled although it will be realized that thereis slightly more lost motion between the movement of the control memberformed as shown in FIG. 14 as compared to control members shown in theother figures.

In both embodiments of the invention, a convenient snap on knob controlmeans has been shown which is economical to assemble and manufacture aswell as serving to provide a cooperation with a detent mechanism.

Although various embodiments of the invention have been shown anddescribed, it is with full awareness that many modifications thereof arepossible. The invention,

therefore, is not to be restricted except as necessitated by the priorart and the spirit of the appended claims What is claimed as theinvention is:

1. In combination, a detent mechanism at a fixed location, a lever armmember having an end portion operable for limited movement to and fromsaid fixed location, and a control member connected to said lever armmember, said control member comprising an elongated body having firstand second ends, knob means connected with said first end, saidelongated body intermediate its first and second ends having a portionof reduced vertical dimension constituting a weakest section forvertical flexure of said elongated body, a recess between said secondend and said portion of reduced vertical dimension, and cam meansbetween said second end and said recess, said cam means, when forceablycontacted by said end of said lever arm, causing said second end tdeflect at said portion of reduced vertical dimension permitting saidend of the lever arm to override said cam means and to be engaged insaid recess.

2. The combination set forth in claim 1 wherein said detent mechanism isformed with a through aperture for receipt of said control member forrelative movement therein and said lever arm member is mounted forlimited pivotal movement in a plane coincident with the axis of saidthrough aperture in said detent mechanism.

3. A control member for insertion into an aperture to engage the end ofa lever arm operable in a plane substantially transverse to the axis ofsaid aperture comprising an elongated body having first and second ends,

knob means connected with said first end, said body intermediate itsfirst and second ends having a portion of reduced vertical dimensionconstituting a weakest section for vertical flexure of said elongatedbody, a recess between said portion of reduced vertical dimension andsaid second end, and cam means between said second end and said recess,said cam means, when forceably contacted by said end of said lever arm,causing said second end to deflect at said portion of reduced verticaldimension permitting said end of the lever arm to override said cammeans and be engaged in said recess.

4. The control member according to claim 3 in which a surface of saidelongated body has at least one depression serving as a travel limit forcoaction with a detent means.

5. The control member according to claim 3 in which a surface of saidelongated body has at least two depressions interconnected by acurvilinear surface, said depressions serving as travel limits forcoaction with a detent means.

6. The control member according to claim 3 in which said elongated bodyis essentially rectilinear in crosssectional area.

References Cited by the Examiner UNITED STATES PATENTS 2,304,356 12/1942Heller 74527 X MILTON KAUFMAN, Primary Examiner.

1. IN COMBINATION, A DETENT MECHANISM AT A FIXED LOCATION; A LEVER ARMMEMBER HAVING AN END PORTION OPERABLE FOR LIMITED MOVEMENT TO AND FROMSAID FIXED LOCATION, AND A CONTROL MEMBER CONNECTED TO SAID LEVER ARMMEMBER, SAID CONTROL MEMBER COMPRISING AN ELONGATED BODY HAVING FIRSTAND SECOND ENDS, KNOB MEANS CONNECTED WITH SAID FIRST END, SAIDELONGATED BODY INTERMEDIATE ITS FIRST AND SECOND ENDS HAVING A PORTIONOF REDUCED VERTICAL DIMENSION CONSTITUTING A WEAKEST SECTION FORVERTICAL FLEXTURE OF SAID ELONGATED BODY, A RECESS BETWEEN SAID SECONDEND AND SAID PORTION OF REDUCED VERTICAL DIMENSION, AND CAM MEANSBETWEEN SAID SECOND END AND SAID RECESS, SAID CAM MEANS, WHEN FORCEABLYCONTACTED BY SAID END OF SAID LEVER ARM, CAUSING SAID SECOND END TODEFLECT AT SAID PORTION OF REDUCED VERTICAL DIMENSION PERMITTING SAIDEND OF THE LEVER ARM TO OVERRIDE SAID CAM MEANS AND TO BE ENGAGED INSAID RECESS.